probably need more info (put it in a sentence) I've not seen "because" used much because of the troubling philosophical implications...But to take a stab, it sounds like it's saying B is a necessary condition for A, so A-->B and ~B-->~A.

To get a valid answer about proper interpretation of the premise OP posted requires more information and context (like at least a full or semi-full sentence).

The word BECAUSE typically functions as a premise indicator and by itself does not definitively establish which element is a sufficient vs. necessary if the use of it in context actually establishes a conditional relationship, which it may or may not do depending on the usage within the context of the argument.

If it is being used to state a cause and effect relationship, then the part after because would be the cause and could be treated as a sufficient condition.

For example: The streets are wet today BECAUSE it rained this morning.

In terms of A because B, A would be 'streets are wet' and B would be 'rained this morning', making B (rained this morning) the sufficient condition to be able to validly conclude the necessary condition that the streets are wet.

Hence B ---> A

In this example 'rained this morning' would not be a necessary condition for the streets being wet. A fire hydrant could have exploded, city services could be driving street sweepers around hosing off the streets, etc.

However, with different phrasing in a full sentence/argument context because could instead refer to something that is a necessary condition or introduce a phrase that itself establishes a full conditional relationship that establishes both the sufficient and necessary conditions. It depends on what the word 'because' actually refers to, meaning the entirety of the sentence(s) it is meant to refer to.